Direct-Write Lithography Recipes
Maskless Aligner (Heidelberg MLA150)
Photolithography Recipes for the Heidelberg MLA150. All recipes were characterized on blank Silicon wafers. For different substrate coatings/materials, you will likely need to run a focus-exposure matrix ("series" exposure mode), using our params as a starting point.
These recipes use the same spin and bake params as our contact aligner and stepper recipes, using built-in hotplates on the photoresist spinner benches.
Positive Resist (MLA150)
We found that positive PR's worked well with the 405nm laser - the 375nm laser would likely also work. Sub-micron features are possible. Overexposure is recommended to avoid stitching and horiz/vert discrepancies, compensate using CD Bias as described here.
| Resist | Spin Cond. | Bake | Thickness | Laser (nm) | Exposure Dose (mJ/cm2) | DeFocus | PEB | Developer | Developer Time | Comments |
|---|---|---|---|---|---|---|---|---|---|---|
| AZ4110 | 4 krpm, 30s | 95°C, 60s | ~ 1.1 µm | 405 | 240 | 5 | none | AZ400K:DI 1:4 | 50s | Used MLA design (good for isolated lines 0.8-1um) |
| AZ4330 | 4 krpm, 30s | 95°C, 60s | ~ 3.3 µm | 405 | 320 | 6 | none | AZ400K:DI 1:4 | 90s | Used MLA design |
| AZ4620 | ||||||||||
| SPR 220-3.0 | 2.5 krpm, 30s | 115°C, 90s | ~ 2.7 µm | 405 | 325 | - 4 | 115°C, 90s | AZ300MIF | 60s | Used MLA design |
| SPR 955-CM0.9 | 3 krpm, 30s | 95°C, 90s | ~ 0.9 µm | 405 | 250 | - 7 | 110°C, 90s | AZ300MIF | 60s | Used MLA design |
| THMR-3600HP | 1.5 krpm, 45s;
250 rpm/s |
100°C, 60s | 0.430µm | 405 | 180–220 | -4 | 100°C, 60s | AZ300MiF | 20s | ~0.4nm line/space:
lower dose for clear-field, higher dose for dark-field. |
Negative Resist (MLA150)
We found that all the negative PR's we tested required the 375nm in order to be fully exposure with reasonable dose.
| Resist | Spin Cond. | Bake | Thickness | Laser (nm) | Exposure Dose (mJ/cm2) | DeFocus | PEB | Flood | Developer | Developer Time | Comments |
|---|---|---|---|---|---|---|---|---|---|---|---|
| AZ5214 | 6 krpm, 30s | 95°C, 60s | ~ 1.0 µm | 375 | 35 | - 5 | 110°C, 60s | 60" | AZ300MIF | 60s | Used UCSB design. Good for up to ~1.3um open line space. |
| AZnLOF2020 | 4 krpm, 30s | 110°C, 60s | ~ 2.1µm | 375 | 340 | - 3 | 110°C, 60s | none | AZ300MIF | 90s | Used UCSB design. Good for 2um open line space. |
| SU-8 2075 | ~70µm | 375 | Extremely viscous. Pour into a wide-mouthed bottle, dispense directly from bottle. Replace napkin at end. |
Greyscale Lithography (MLA150)
AZ4620 is the manufacturer-recommended PR for greyscale litho.
| Resist | Spin Cond. | Bake | Thickness | Exposure Dose (mJ/cm2) | Focus Offset | PEB | Flood | Developer | Developer Time | Comments |
|---|---|---|---|---|---|---|---|---|---|---|
| AZ4620 | – krpm/30” | 95°C, 60” | 60" | AZ300MIF | 60s |
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